/* Copyright 2013-2015 www.snakerflow.com.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.snaker.engine.spring;

import java.util.Map;
import java.util.Map.Entry;
import org.snaker.engine.Expression;
import org.springframework.expression.EvaluationContext;
import org.springframework.expression.ExpressionParser;
import org.springframework.expression.spel.standard.SpelExpressionParser;
import org.springframework.expression.spel.support.StandardEvaluationContext;

/**
 * Spring el表达式解析器
 * 
 * @author yuqs
 * @since 1.2.2
 */
public class SpelExpression implements Expression {
    ExpressionParser parser = new SpelExpressionParser();

    /**
     * 表达式解析
     */
    public <T> T eval(final Class<T> T, final String expr, final Map<String, Object> args) {
        EvaluationContext context = new StandardEvaluationContext();
        if (args != null && args.size() > 0) {
            for (Entry<String, Object> entry : args.entrySet()) {
                context.setVariable(entry.getKey(), entry.getValue());
            }
        }
        return parser.parseExpression(expr).getValue(context, T);
    }
}
